KR101460442B1 - Harmonic Voltage Compensator with Repetitive Controller - Google Patents

Abstract

The present invention relates to an apparatus for removing the harmonics of a voltage included in a point of common coupling in a voltage compensator and, more particularly, to a voltage compensator capable of forming a sine wave regardless of the kind of a load by removing all odd harmonics included in the point of common coupling using two repetitive controllers.

Description

[0001] Harmonic Voltage Compensator with Repetitive Controller [

The present invention relates to a device for eliminating voltage harmonics included in a common terminal (Point of Common Coupling) in a voltage compensation device, and more particularly, to a device for eliminating voltage harmonics contained in a common terminal (Point of Common Coupling) using two repetitive controllers Common Coupling) to eliminate all odd harmonics and to make a sine wave irrespective of the type of load.

The voltage compensating device is a device for preventing the voltage supplied to the load from being distorted due to the unbalance or nonlinearity of the load. It eliminates the phenomenon that the voltage is distorted by the harmonic component when the voltage is supplied so that the undistorted sinusoidal voltage is applied to the load .

Methods of providing electricity to the load while preventing such voltages from distorting include grid-connected operations that regulate the supply of electricity with the help of utility companies, There is a stand-alone system that supplies electricity directly to the load without assistance, and the voltage compensation device is used in such a stand-alone electrical supply system. In the case of a stand-alone system, there are many distorted signals in the process of providing the voltage because the electricity is produced and supplied to the load without the help of the utility company. Since the system operates as its own system, It is necessary to remove the distortion signals and supply electric power to the load.

In recent years, as the use of reuse energy has increased, a self-generated power system has been activated, and it has become necessary to produce and supply electricity in a city where electricity supply is not smooth. Thus, There is an increasing demand for a voltage compensation device for eliminating distorted voltages and supplying a sufficient amount of electricity.

1, a stand-alone system includes a Distributed Generation System (DG) 110, a Point of Common Coupling (PCC) 120, and a Load A sinusoidal wave generated by the distributed power source unit 110 is supplied through the common terminal 120. If the load 130 is unbalanced or nonlinear, And a distorted voltage is supplied.

In order to compensate for such a distorted voltage, PI controller, predictive control, adaptive control, multiple resonant controller and repetitive control of a plurality of reference frames have been used.

However, since the PI controller is adjustable only for a single voltage signal, the system can be complicated due to the necessity of a plurality of PI controllers in a system in which various combinations of voltage signals are present. Predictive control can expect excellent performance and quick response Adaptive Control can regulate the load voltage by measuring the load current, but there is an inconvenience that a separate operation is required when the load is changed. The Resonant Controller There is a disadvantage in that a plurality of resonant controllers are required because only one specific voltage signal can be compensated.

A voltage compensation method using a repetitive controller has been proposed as an alternative to solve the problems of various types of compensation methods. The iterative controller can provide excellent performance, but only a single dominant signal component can be compensated so that there is a limit to removing all harmonics when there are multiple harmonic voltage controllers Disadvantages existed.

2, in the voltage compensator 202 using the conventional PI controller 203 and the repetitive controller 204, the PI controller 203 controls the basic frequency component of the voltage of the common terminal 201 And the repetitive controller 204 has a role of preventing harmonic waves from being distorted due to line resistance and load imbalance. However, since the conventional voltage compensating apparatus 202 uses only one repetition controller 204, only a single dominant signal can be compensated for, resulting in a slow response time and a time delay, There is a problem that the voltage can not be compensated effectively.

US registered patent 7,904,495 Korean Patent No. 10-1212830

The present invention is to provide a voltage compensation device that compensates for a common terminal voltage and has a fast response speed by eliminating all odd harmonics of a common terminal voltage by using two repetitive controllers.

1(n은 자연수)인 고조파 성분이고, 상기 제 1 전달함수 게인이 상기 제 1 고조파의 주파수에서 최대값을 가지도록 상기 제 1 전달함수의 계수를 제어하여 상기 입력 신호의 상기 제 1 고조파 성분과 결합되도록 하는 것을 특징으로 하는 고조파 전압 보상 장치를 제공할 수 있다.A harmonic voltage compensating apparatus according to one aspect of the present invention is a harmonic voltage compensating apparatus for compensating for a distortion voltage of a common terminal. The harmonic voltage compensating apparatus includes a first harmonic voltage compensating unit for converting a first input signal to a common coordinate, A first repetition controller for removing harmonic components; And a second repetitive controller for converting the input signal coming into the common terminal into a fixed coordinate system to remove a second harmonic component, wherein the first and second repetitive controllers output the input signal having the odd- Is supplied to the load. The first repetition controller has a first transfer function, which is a first output signal value relative to the first input signal, and includes a first time delay unit for determining whether the first transfer function is time delayed or not. A first phase control unit for determining a phase difference of the first transfer function; A first gain determiner for adjusting the first transfer function gain according to an input frequency; And a first signal filter for filtering the input signal according to the input frequency, wherein the first harmonics include 6n

1 (where n is a natural number), and controls the coefficients of the first transfer function so that the first transfer function gain has a maximum value at the frequency of the first harmonic, so that the first harmonic component of the input signal and So that the harmonic voltage compensation device can be provided.

Also, the first signal filter unit may be a low-pass filter that does not change the phase of the first transfer function.

The second repetition controller may include a second time delay unit having a second transfer function which is a second output signal value relative to the second input signal and determining whether the second transfer function is time delayed or not; A second phase control unit for determining a phase difference of the second transfer function; A second gain determiner for adjusting the second transfer function gain according to an input frequency; And a second signal filter for filtering the input signal according to the input frequency.

3(n은 자연수)인 고조파 성분이고, 상기 제 2 전달함수의 게인이 상기 제 2 고조파의 주파수에서 최대값을 가지도록 상기 제 2 전달함수의 계수를 제어하여 상기 입력 신호의 제 2 고조파 성분과 결합되도록 하는 것을 특징으로 하는 고조파 전압 보상 장치일 수 있으며, 상기 제 2 신호 필터부는 상기 제 2 전달 함수의 위상을 변화시키지 않는 저역 통과 필터인 것을 특징으로 하는 고조파 전압 보상 장치일 수 있다.
At this time, the second harmonic is 6n

(N is a natural number), and controls the coefficient of the second transfer function so that the gain of the second transfer function has a maximum value at the frequency of the second harmonic, so that the second harmonic component of the input signal And the second signal filter unit is a low-pass filter that does not change the phase of the second transfer function. The harmonic voltage compensator may be a harmonic voltage compensator.

The present invention has the effect of eliminating all the odd-order harmonics and reducing the delay time and speeding up the response speed by designing the voltage compensator using two repetitive controllers.

FIG. 1 is a schematic diagram illustrating a process of supplying a voltage to a load according to an embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating a process of supplying a voltage to a load by applying a PI controller and a repetitive controller according to an embodiment of the present invention;
3 is a graph showing voltage characteristics when various types of loads are connected to a distributed power source apparatus according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a process in which a repetitive controller is applied to a distributed power supply according to a preferred embodiment of the present invention,
FIG. 5 is a diagram illustrating the components of a first repetitive controller as a preferred embodiment of the present invention,
FIG. 6 is a diagram illustrating the components of a second repetitive controller according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a method of operating a repeater controller according to a preferred embodiment of the present invention,
8 is a schematic diagram of a system to which two repetitive controllers are applied in accordance with an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

3 is a graph showing voltage characteristics when various types of loads are connected to a distributed power source apparatus according to an embodiment of the present invention.

는 선로의 저항(302),

는 선로의 인덕턴스(303),

는 공통 단자 전압(304)이며,

는 입력 전압(301)이다. 상기 입력 전압(301)을 기준으로 상기 분산 전원 장치를 통해 상기 공통 단자에 제공되는 전압은 상기 선로의 저항(302) 및 상기 선로의 인덕턴스(303)에 의해 크기 및 위상이 변화되며 식은 아래와 같다.Referring to Figure 3,

The resistance of the line 302,

The inductance 303 of the line,

Is a common terminal voltage 304,

Is the input voltage (301). The magnitude and phase of the voltage supplied to the common terminal through the distributed power supply unit based on the input voltage 301 are changed by the resistance 302 of the line and the inductance 303 of the line.

과 상기 선로의 저항(302) 및 상기 선로의 인덕턴스(303)에 의해 생기는 손실 값을 상기 입력 전압(301)에서 뺀 값이 되며, 상기 선로의 인덕턴스(303)에 의해서는 위상 변화가 생길 수 있다. 또한, 선로에 흐르는 상기 전류

은 상기 부하의 종류에 따라 변화되는데 불균형 부하(305)에서 상기 전류

은 크기 및 위상이 모두 변하게 된다. 이러한 변화에 의해 상기 공통 단자 전압(304)에서 상기 고조파 성분이 포함될 수 있으며, 이러한 상기 고조파 성분이 포함된 전압이 상기 공통 단자 전압(304)에 걸리게 되면 결과적으로 상기 부하에 왜곡된 전압이 생기게 된다.Referring to Equation 1, the common terminal voltage 304 is a current flowing in the line

A resistance value of the line 302 and an inductance 303 of the line are subtracted from the input voltage 301 and a phase change may be caused by the inductance 303 of the line . Also, the current flowing in the line

Is varied depending on the type of the load. In the unbalanced load 305,

Both the magnitude and the phase are changed. By this change, the harmonic component can be included in the common terminal voltage 304. When a voltage including the harmonic component is caught by the common terminal voltage 304, a distorted voltage is generated in the load .

In a preferred embodiment of the present invention, when the load is a three-phase diode rectifier, in the case of the three-phase load,

1(n은 자연수)의 고조파를 시스템에 포함되게 된다. 이는 상기 부하가 3상으로 구성되어 있는바, 서로 다른 3개의 위상 값이 존재하기 때문인 것으로 일반적으로 알려진 사실이다. 이러한 값을 상기 공통 단자 전압을 구하는 식에 적용하면 하기와 같이 된다.6n for

1 (n is a natural number) harmonics are included in the system. This is generally known to be due to the fact that the load is composed of three phases and that there are three different phase values. This value is applied to the equation for obtaining the common terminal voltage as follows.

및

은 기본 주파수만이 포함되었을 경우의 전압 및 전류를 의미하며

은 고조파 성분에 대한 부하 전류를 의미하는 것으로, 상기 식2에서 입력 전압인

이 순수한 정현파의 경우라도 결과 값인 상기 공통 단자 전압은 고조파 성분이 포함된 왜곡된 값인 것을 볼 수 있다. 따라서 실제적으로 필요로 하는 값인 상기 공통 단자 전압이 순수한 정현파가 되기 위해서는 상기 고조파 성분을 보상하여 원상태로 만들기 위한 장치가 필요하며, 이러한 장치로서 상기 반복 제어기를 이용하게 된다.In the above equation

And

Refers to the voltage and current when only the fundamental frequency is included

Denotes a load current for a harmonic component, and in Equation 2,

Even in the case of this pure sine wave, it can be seen that the resultant common terminal voltage is a distorted value including a harmonic component. Therefore, in order for the common terminal voltage, which is a practically necessary value, to be a pure sinusoidal wave, a device is required to compensate for the harmonic component to restore the harmonic component, and the repetitive controller is used as such a device.

4, a PI controller and a repetitive controller are applied to a distributed power supply according to an embodiment of the present invention. Referring to FIG. 4, the PI controller 401 and the repetitive controller 402 To remove the harmonics. At this time, the repetitive controller 402 is included between the distributed power supply 110 and the common terminal 120 to remove the harmonics and remove the harmonics from the common terminal voltage, . The repetitive controller 402 has the same value as the harmonic element in Equation (2), and has a mutually opposite value. By removing the harmonic element of Equation (2) to cancel it, only the fundamental frequency exists, To the load (130).

값을 가지며, 이때 N은 기본 주파수 동안의 샘플링 되는 수로서 상기 제 1 및 제 2 전달 함수의 전체 시간 지연 여부를 결정하게 되고, 상기 위상 제어부(502, 602)는

값을 가지면서 상기 제 1 및 제 2 전달 함수의 위상을 조절하게 되며, 상기 게인 결정부(503, 603)는

값을 가지면서 상기 제 1 및 제 2 전달 함수의 게인 값을 조절함에 따라 특정 고조파에 대해서 상쇄할 수 있도록 한다. 또한, 상기 신호 필터부(504, 604)는 Q(z) 값으로 위상을 변화시키지 않으면서 특정 주파수만을 통과시키는 필터 역할을 함으로서, 특정 고조파 성분을 제거할 수 있다.5 and 6 illustrate components of a repetitive controller as a preferred embodiment of the present invention. Referring to FIGS. 5 and 6, the repetitive controller includes time delay units 501 and 601, , Phase control units 502 and 602, gain determination units 503 and 603 and signal filter units 504 and 604 to control the first and second transfer functions of the iterative controller Accordingly, the harmonic components in Equation 2 are removed. Among the components, the time delay units 501 and 601

Where N is the number of samples sampled during the fundamental frequency to determine whether the first and second transfer functions are totally time delayed, and the phase controllers (502, 602)

And controls the phases of the first and second transfer functions while the gain determination units 503 and 603 adjust the phases of the first and second transfer functions

And adjusting the gain values of the first and second transfer functions so as to cancel the harmonics with respect to specific harmonics. In addition, the signal filter units 504 and 604 can remove a specific harmonic component by acting as a filter for passing only a specific frequency without changing the phase to Q (z).

In one preferred embodiment of the present invention, the signal filter units 504 and 604 may be low-pass filters and have the following values.

The signal filter units 504 and 604 are low-pass filters having a large gain value in a signal having a small frequency and a low gain value in a signal having a high frequency. This is because when the input signal has a high frequency The system is unstable and the distortion to the value of the common terminal voltage 304 can be intensified and is applied so as to have a low gain at a high frequency to stabilize the system.

Referring to FIG. 7, the repetitive controller having the above-described components includes a time delay unit 701, a time delay unit 702, The phase controller 702 and the gain determiner 703 are sequentially applied and the signal filter 704 is applied as a feedback process to form the overall transfer function. The transfer function of the repetitive controller will be described below.

은 전달함수의 게인, N은 기본 주파수 동안의 샘플링 수,

는 위상 지연값 및 Q(z)는 신호 필터값이며, 상기와 같은 전달 함수에 의해서 상기 반복 제어기를 통해 고조파 성분에 대한 왜곡을 상쇄시킬수 있도록 한다.In the above formula

Is the gain of the transfer function, N is the number of samples during the fundamental frequency,

And the phase delay value Q (z) is a signal filter value, and the distortion of the harmonic component can be canceled through the repetitive controller by the transfer function as described above.

Therefore, the repetition controller changes the transfer function according to the values of the phase control unit 702, the gain determination unit 703, and the signal filter unit 704, and has the same shape as the harmonic component, The distorted value is removed from the common terminal voltage 304 by compensating for the harmonic component.

However, when the harmonics are removed using one repetition controller, all the odd-order harmonics can not be removed, and when the load 130 suddenly changes due to a slow response speed, the waveform is not maintained. Therefore, in the system configured by only one repeater controller as described above, it is not possible to provide the common terminal voltage 304 having a good performance while effectively removing the distorted signal. Thus, a system using two repeater controllers is implemented, . ≪ / RTI >

FIG. 8 is a schematic diagram of a system to which two repetitive controllers are applied. Referring to FIG. 8, two repetitive controllers can be applied to remove all odd order harmonics. Since the even-order harmonics in the square wave do not distort the load, the load can be prevented from being distorted and the response speed can be increased by removing all the odd-order harmonics as described above.

1(n은 자연수)에 대한 고조파를 보상하여 제거하기 위해 적용된다. 상기 3상 부하는 120

의 위상차가 나는 3개의 부하가 공존하기 때문에 기본 주파수를 기준으로 상기 제 1 고조파인 6n

1(n은 자연수) 고조파만이 생성되게 되며, 상기 제 1 반복 제어기(80)는 상기 3상 부하에 의해 생기는 왜곡을 제거할 수 있도록 한다. 이를 위해서 상기 제 1 반복 제어기(801)는 입력 전원 주파수와 동일한 각속도를 갖는 회전 좌표계(d-q)에서 설계된다. 이는, 상기 제 1 고조파는 상기 회전 좌표계에서 6n(n은 자연수) 고조파처럼 동작하기 때문에 왜곡되는 고조파의 제거가 용이하며, 이때 상기 제 1 반복 제어기(801)의 상기 제 1 전달함수는 하기의 식과 같이 구성 된다.More specifically, referring to FIG. 8, the first repetitive controller 801 calculates a first harmonic component 6n

1 (n is a natural number). The three-phase load is 120

The three harmonics of the first harmonic 6n

1 (n is a natural number) harmonics are generated, and the first iteration controller 80 can eliminate the distortion caused by the three-phase load. To this end, the first iteration controller 801 is designed in a rotational coordinate system (dq) having the same angular velocity as the input power frequency. This is because it is easy to remove distorted harmonics because the first harmonic operates like 6n (n is a natural number) harmonic in the rotation coordinate system, and the first transfer function of the first iteration controller 801 is expressed by the following equation Respectively.

은 제 1 전달함수의 게인, N은 기본 주파수 동안의 샘플링 수,

는 위상 지연값 및 Q(z)는 신호 필터값이다.Equation (5) to Equation (4)

Is the gain of the first transfer function, N is the number of samples during the fundamental frequency,

Is the phase delay value and Q (z) is the signal filter value.

값이

으로 변경된 것으로, 상기 3상 부하에서는 상기 제 1 고조파인 6n

1(n은 자연수)에 대한 고조파만이 발생하기 때문에 상기와 같은 제 1 전달함수만으로도 상기 고조파를 제거할 수 있다. 이와 같이 상기 제 1 전달함수를 조절하기 위해 상기 제 1 위상 제어부(502)에서 위상 지연 값을 제어하며, 상기 제 1 게인 결정부(503)는 상기 제 1 고조파인 6n

1(n은 자연수)의 주파수에서 최대 게인 값을 가지도록 상기와 같이 상기 제 1 전달함수를 조절하여 시스템에서 상기 제 1 고조파인 6n

1(n은 자연수) 고조파를 상쇄하여 제거할 수 있도록 한다.Referring to Equation 5, the first transfer function

The value is

And in the 3-phase load, the first harmonic 6n

1 (where n is a natural number), the harmonics can be removed with only the first transfer function as described above. In order to adjust the first transfer function, the first phase controller 502 controls the phase delay value, and the first gain determiner 503 determines the first harmonic 6n

1 (n is a natural number), the first transfer function is adjusted so that the first harmonic 6n

1 (n is a natural number).

1(n은 자연수) 고조파만을 제거할 수 있을 뿐, 단일 위상을 갖는 불균형 부하에서 발생하는 제 2 고조파인 6n

3(n은 자연수)의 트리플렌 고조파(triplen harmonic)를 제거할 수 없다. 따라서, 이러한 상기 트리플렌 고조파를 제거하기 위해서 제 2 반복 제어기(802)를 고정 좌표계(

)에서 설계하여 상기 제 2 고조파인 트린플렌 고조파를 제거하도록 한다. 상기 제 2 반복 제어기(802)는 단일 위상을 갖는 불균형 부하에서는 상기 제 2 고조파인 6n

3(n은 자연수) 고조파가 발생하기 때문에 상기 회전 좌표계(d-q)가 아닌 상기 고정 좌표계(

)에서 설계되도록 한다. 이를 위해서 상기 제 2 반복 제어기(802)는 제 2 전달함수를 가지며, 상기 제 2 전달함수는 제 2 위상 제어부(602)에서 위상 지연을 제어하며 제 2 게인 결정부(603)에서 상기 제 2 고조파인 6n

3(n은 자연수)의 주파수에서 최대 게인 값을 가지도록 하여 시스템에 발생하는 상기 제 2 고조파인 6n

3(n은 자연수) 고조파를 상쇄시킬 수 있도록 한다. 상기 제 2 반복 제어기(802)는 상기 고정 좌표계(

)에서 상기 제 2 고조파인 6n

3(n은 자연수) 고조파를 제거하기 위한 방법으로 하기와 같은 상기 제 2 전달 함수를 갖게 된다.However, the first iterative controller 801 is configured to control the first harmonic 6n

1 (n is a natural number) harmonics can be removed, and the second harmonic 6n

3 (n is a natural number) triplen harmonic can not be removed. Therefore, in order to remove the triplen harmonics, the second repetition controller 802 is connected to a fixed coordinate system

To remove the trinflene harmonic of the second harmonic. The second iterative controller 802 receives the second harmonic 6n in an unbalanced load having a single phase,

3 (n is a natural number) harmonics are generated. Therefore, the rotation coordinate system (dq)

). For this, the second repetition controller 802 has a second transfer function, the second transfer function controls the phase delay in the second phase controller 602, the second gain determiner 603 determines the second harmonic 6n

3 (n is a natural number), and the second harmonic 6n

3 (n is a natural number) harmonics can be canceled. The second iterative controller 802 receives the fixed coordinate system

), The second harmonic 6n

3 (where n is a natural number) harmonic, and has the second transfer function as described below.

은 제 2 전달함수의 게인, N은 기본 주파수 동안의 샘플링 수,

는 위상 지연값 및 Q(z)는 신호 필터값이다. 상기 식 6과 같은 상기 제 2 전달함수를 포함하는 상기 제 2 반복 제어기(802)는 상기 제 2 고조파인 6n

3(n은 자연수) 주파수에서 최대 게인 값을 가지게 되어 시스템에서 상기 제 2 고조파를 상쇄시켜 고조파를 제거하게 된다.As in Equation 6, Equation 4

Is the gain of the second transfer function, N is the number of samples during the fundamental frequency,

Is the phase delay value and Q (z) is the signal filter value. The second repetition controller 802 including the second transfer function as shown in Equation (6) can calculate the second harmonic 6n

3 (where n is a natural number) frequency to cancel harmonics by canceling the second harmonics in the system.

1(n은 자연수)의 고조파를 제거하며, 상기 제 2 반복 제어기(802)는 상기 제 2 고조파인 6n

3(n은 자연수)의 고조파를 제거할 수 있기 때문에 상기 제 1 및 제 2 반복 제어기(801, 802)를 구비한 상기 분산 전원 장치는 모든 상기 홀수차 고조파를 제거할 수 있게 되며, 구형파의 모든 상기 짝수차 고조파는 서로 상쇄되어 없어지게 되는바 상기 공통 단자에서 왜곡되지 않은 정현파를 제공할 수 있게 된다. Therefore, the first iteration controller 801 receives the first harmonic 6n

1 (n is a natural number), and the second repetition controller 802 removes harmonics of the second harmonic 6n

3 (n is a natural number) harmonics can be removed. Therefore, the distributed power supply apparatus having the first and second repetitive controllers 801 and 802 can remove all the odd-order harmonics, The even-order harmonics cancel each other out, so that sinusoidal waves not distorted at the common terminal can be provided.

In addition, by removing the first, second, and even-order harmonics, all the harmonics can be removed only by the transfer function having the reduced time of 1/6 times. As a result, It is possible to improve the performance of the system while removing the distortion signal so as to reduce it to 1/6 times.

110: Distributed power supply device 120: Common terminal
130: load 201: common terminal
202: Voltage compensator 203: PI controller
204: Repeat controller 205: Load
301: Input voltage 302: Line resistance
303: Line inductance 304: Common terminal voltage
305: Unbalanced load 401: PI controller
402 Repetition controller 501: First time delay unit
502: first phase control unit 503: first gain determination unit
504: first signal filter unit 601: second time delay unit
602: second phase control unit 603: second gain determination unit
604: Second signal filter unit 701: Time delay unit
702: phase control unit 703: gain determination unit
704: Signal filter unit 801: First repetition controller
802: second repetition controller

Claims (7)

A harmonic voltage compensating apparatus for compensating for a distortion voltage of a common terminal,
A first repetitive controller for converting an input signal input to the common terminal into a rotational coordinate system having an angular velocity equal to an input power supply frequency to remove a first harmonic component; And
And a second repetitive controller for converting the input signal coming into the common terminal into a fixed coordinate system to remove a second harmonic component,
The input signal from which odd-order harmonics have been removed by the first and second repeating controllers is supplied to the load,
Wherein the first repetition controller comprises:
A first time delay unit having a first transfer function that is a first output signal value relative to the first input signal and determining whether the first transfer function has a time delay;
A first phase control unit for determining a phase difference of the first transfer function;
A first gain determiner for adjusting the first transfer function gain according to an input frequency;
And a first signal filter for filtering the input signal according to the input frequency.
delete The method according to claim 1,
The first harmonic is 6n

1 (n is a natural number)
Wherein the coefficient of the first transfer function is controlled to be combined with the first harmonic component of the input signal so that the first transfer function gain has a maximum value at the frequency of the first harmonic. .
The method according to claim 1,
Wherein the first signal filter unit is a low-pass filter that does not change the phase of the first transfer function.
The method according to claim 1,
Wherein the second iteration controller has a second transfer function that is a second output signal value relative to the second input signal,
A second time delay unit for determining whether the second transfer function is delayed or not;
A second phase control unit for determining a phase difference of the second transfer function;
A second gain determiner for adjusting the second transfer function gain according to an input frequency;
And a second signal filter for filtering the input signal according to the input frequency.
6. The method of claim 5,
The second harmonic is 6n

3 (n is a natural number)
And the coefficient of the second transfer function is controlled to be combined with the second harmonic component of the input signal so that the gain of the second transfer function has a maximum value at the frequency of the second harmonic. .
6. The method of claim 5,
Wherein the second signal filter unit is a low-pass filter that does not change the phase of the second transfer function.

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